Optical fiber for generating bessel beam and optical imaging device using same

Abstract

An optical fiber for generating a Bessel beam and an optical imaging device using the same are disclosed. The optical fiber for generating a Bessel beam includes a single mode optical fiber (SMF) unit, a multi-mode optical fiber unit, and a lens unit. The SMF unit includes a core and a cladding surrounding the core. The multi-mode optical fiber unit comes in contact with a first end of the SMF unit. The lens unit comes in contact with one end of the multi-mode optical fiber unit that faces the first end of the SMF unit.

What is claimed is: 
     
         1 . An optical fiber for generating a Bessel beam, comprising:
 a single mode optical fiber (SMF) unit configured to include a core and a cladding surrounding the core;   a multi-mode optical fiber unit configured to come in contact with a first end of the SMF unit; and   a lens unit configured to come in contact with one end of the multi-mode optical fiber unit that faces the first end of the SMF unit.   
     
     
         2 . The optical fiber of  claim 1 , wherein a difference in a relative refractive index between the core and the cladding is 1%. 
     
     
         3 . The optical fiber of  claim 1 , wherein:
 the core has a diameter of 3.4 μm; and   the cladding has an external diameter of 125 μm.   
     
     
         4 . The optical fiber of  claim 3 , wherein the multi-mode optical fiber unit has a diameter identical to an external diameter of the cladding. 
     
     
         5 . The optical fiber of  claim 1 , wherein the multi-mode optical fiber unit comprises a coreless silica optical fiber (CSF). 
     
     
         6 . The optical fiber of  claim 1 , wherein the lens unit has a curvature radius in a range from 62.5 to 82 μm. 
     
     
         7 . An optical imaging device using an optical fiber for generating a Bessel beam according to  claim 1 . 
     
     
         8 . The optical imaging device of  claim 7 , wherein the optical imaging device comprises any one of a photo-acoustic tomography apparatus, a photo-acoustic microscope, a photo-acoustic endoscope, a photo-acoustic laparoscope for operation, an optical interference tomography apparatus, a fluorescent imaging apparatus, and a multi-photon microscope using the optical fiber for generating a Bessel beam. 
     
     
         9 . The optical imaging device of  claim 8 , wherein the photo-acoustic microscope comprises:
 an optical unit configured to provide light to a second end of the SMF unit; and   a detection unit configured to detect ultrasonic waves generated by a sample when a Bessel beam generated by the optical fiber for generating a Bessel beam is incident on the sample.   
     
     
         10 . The optical imaging device of  claim 9 , wherein the optical unit comprises:
 a pulse laser configured to generate the light;   a beam splitter configured to split the light into two;   a photodiode configured to receive a first piece of light and send a trigger signal to the detection unit; and   an optical fiber collimator configured to receive a second piece of light and send the second piece of light to the optical fiber for generating a Bessel beam.   
     
     
         11 . The optical imaging device of  claim 10 , wherein the optical unit further comprises:
 a collimation lens disposed between the pulse laser and the beam splitter; and   a neutral density filter disposed between the beam splitter and the optical fiber collimator.   
     
     
         12 . The optical imaging device of  claim 9 , wherein the detection unit comprises:
 an ultrasonic transducer configured to convert the ultrasonic waves generated by the sample into a photo-acoustic signal; and   a data processing unit configured to convert the photo-acoustic signal from the ultrasonic transducer into an image.   
     
     
         13 . The optical imaging device of  claim 12 , further comprising:
 an ultrasonic amplifier disposed between the ultrasonic transducer and the data processing unit and configured to amplify the photo-acoustic signal; and   a data acquisition unit configured to obtain the amplified photo-acoustic signal and send the obtained photo-acoustic signal to the data processing unit.